The invention relates to an electronic monitoring device for a battery which is constructed from a plurality of physically separated blocks. Traction batteries for electric vehicles, for example, form an important application and are frequently constructed in this way.
The service life of present-day traction batteries is usually substantially shorter than the service life of the vehicle in which they are installed. In conventional electronic monitoring devices for traction batteries, the battery data acquisition and storage units are usually designed so that they remain when the battery is changed. The conventional electronic monitoring devices without a ring circuit system require a relatively high outlay on cabling in order to fulfil the diverse electronic functions.
Devices of this type are disclosed, for example, German Patent Documents DE OS 34 12 541 A1 and DE OS 37 02 591 A1. The ring circuit systems in these publications are formed by simple electronic control signal and/or measurement signal leads, with the measurement data being successively interrogated by the individual measuring circuit modules, either by means of an address-encoded control signal from the central unit or as a result of successive control signals being passed on from one measuring circuit module to the next. The measurement data are transferred to the central unit without the individual measuring circuit modules having access to it.
One object of the invention is to provide an electronic monitoring device for the aforesaid type of batteries, which can monitor the battery status easily, reliably and with a low outlay on cabling.
This and other objects and advantages are achieved by the electronic battery monitoring device according to the invention, in which each battery block has assigned to it a separate measuring circuit module which is fed by the battery and which detects the necessary measured variables, such as its voltage and temperature. The individual measuring circuit modules are connected to one another with extremely small outlay on cabling by means of a simple serial databus. Furthermore, a central data processing unit, which is arranged outside the battery, is connected to the serial databus. The data processing unit, for example, a microprocessor, evaluates the battery status data and contains the more complex electronic functions.
When the battery is changed, as is necessary from time to time in the case of a vehicle traction battery, the more complex electronic functions therefore remain in the vehicle while the simple electronic functions, which are integrated into the battery in the form of the measuring circuit modules and the serial databus, are disposed of with the battery. Therefore, all that is necessary to change the battery is to uncouple the serial databus from the central data processing unit and the battery poles from the outgoing battery current lead and recouple them correspondingly.
In a preferred embodiment, a central data memory which is physically linked to one of the battery blocks and connected to the serial databus, stores the data relevant to the battery. This memory is preferably of non-volatile configuration, and is thus not reused when the battery is changed. Preferably, it is also protected against unauthorized tampering, which is especially expedient for independent battery systems, such as batteries in rental cars.
Another embodiment permits maximum simplification of the serial databus in that all the measurement data of all the measuring circuit modules are transmitted in packets. Each measuring circuit module removes the information required by it from the respective measurement packet passing via the databus and adds the measurement data which it has acquired itself. The protocol and transmission format on the serial databus are best designed so that the individual measuring circuit modules can have an identical hardware design.
According to another feature of the invention, capacitive coupling of the measuring circuit modules to one another can be realized very cost-effectively, especially in comparison with the alternative of connecting the measuring circuit modules by means of opto-couplers.